KR101853601B1 - Noise reduction structure and supercharging device - Google Patents

Abstract

The noise reduction structure includes a first perforated plate portion extending along the inner peripheral surface in the circumferential direction of the compressor discharge side piping portion so as to form an air layer between the compressor discharge side piping portion and the inner peripheral surface of the compressor discharge side piping portion and having a plurality of through holes, A partition portion for partitioning the internal space of the compressor discharge side piping portion in the radial direction or the circumferential direction of the compressor discharge side piping portion to form a plurality of flow paths in the compressor discharge side piping portion, And a second porous plate portion extending along the partition portion to form an air layer and having a plurality of through holes.

Description

TECHNICAL FIELD [0001] The present invention relates to a NOISE REDUCTION STRUCTURE AND SUPERCHARGING DEVICE,

The present invention relates to a noise reduction structure and a supercharging apparatus.

As an auxiliary device for obtaining high combustion energy in an internal combustion engine, a supercharger is widely used. For example, an exhaust turbine type supercharger is configured to compress a turbine, which is coaxially connected to a compressor, with exhaust gas of an internal combustion engine to compress air supplied to the internal combustion engine by a compressor.

Recently, there is a growing demand for noise reduction of superchargers. Patent Document 1 discloses a muffling device for reducing noise on the air discharge side of a compressor of a turbocharger. In such a muffler, the pipe between the outlet pipe of the compressor and the air cooler in the supercharger is of a double pipe structure comprising an outer pipe and an inner pipe. A resonance cavity is formed between the outer tube and the inner tube, and a plurality of through holes communicating with the resonance cavity are formed in the inner tube. In this configuration, by setting the volume of the resonance cavity, the cross-sectional area and the length of the through-hole in correspondence to the resonance frequency in accordance with the rotation period of the blower, it is possible to reduce the number of rotations of the compressor impeller, Noise) can be reduced.

Japanese Patent Publication No. 4911783

According to the silencer disclosed in Patent Document 1, the noise on the air discharge side of the supercharger can be reduced. However, due to the space limitations between the compressor and the air cooler in the supercharger, Therefore, the effect of noise reduction is likely to be limited.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a noise reduction structure capable of effectively reducing noise on the air discharge side of a compressor in a supercharger and a supercharger having the same .

(1) A noise reduction structure according to at least one embodiment of the present invention is a noise reduction structure for reducing noise on the air discharge side of a compressor in a supercharger, wherein a noise reduction structure for reducing noise on a side of a tongue portion of a vortex chamber of the compressor, An air layer is formed between the compressor discharge-side piping portion, which is a piping of at least a part of the compressor discharge-side piping, which is composed of the compressor outlet piping on the downstream side and the piping connecting the compressor discharge piping and the air cooler, and the inner peripheral surface of the compressor discharge- A first porous plate portion extending along the inner peripheral surface in the circumferential direction of the compressor discharge-side piping portion and having a plurality of through holes to divide the inner space of the compressor discharge-side piping portion in the radial direction or the circumferential direction of the compressor discharge- , A plurality of flow paths are formed in the compressor discharge side piping section Is formed in each partition portion with the plurality of flow paths, and extending along parts of the cell so as to form an air layer between said partition portion, the second portion is provided with a perforated plate having a plurality of through-holes.

According to the noise reduction structure described in (1) above, since the first perforated plate portion and the air layer function as an acoustic filter and the second perforated plate portion and the air layer function as an acoustic filter, Can be reduced.

Further, as compared with the case where only the first perforated plate portion is formed in the compressor discharge-side pipe portion, since the partition portion and the second perforated plate portion are formed, the installation area of the perforated plate portion can be increased. Therefore, the noise reduction effect per unit length of the compressor discharge side piping portion is improved, and the noise on the air discharge side of the compressor can be effectively reduced.

(2) In some embodiments, in the noise reduction structure described in (1), the partitioning portion may include a plurality of radially extending portions for dividing the internal space of the compressor discharge-side piping portion into the plurality of flow paths in the circumferential direction And a partition plate portion.

According to the noise reduction structure described in (2) above, since the second perforated plate portion extends along both surfaces of the partition plate portion extending in the radial direction, the noise reduction effect per unit length of the compressor discharge side pipe portion is improved, The noise reduction effect can be obtained. In addition, manufacturing of the noise reduction structure can be facilitated. For example, by inserting the partition portion into the compressor discharge-side piping portion from the one end side of the compressor discharge-side piping portion and connecting the outer end in the radial direction of the partitioning plate portion to the inner peripheral surface of the compressor discharge-side piping portion by welding or the like, It can be easily fixed to the compressor discharge side piping portion. In addition, since the compressor discharge-side pipe portion is supported from the inside by the plurality of partition plates extending in the radial direction, the high rigidity can be realized.

(3) In some embodiments, in the noise reduction structure described in (2), the partition portion has a cross-sectional shape such that it divides the internal space of the compressor discharge-side piping portion into four flow paths in the circumferential direction .

According to the noise reduction structure described in (3) above, since the second perforated plate portion extends along both surfaces of the four partition plates extending in the radial direction, a total of eight second perforated plate portions extending in the radial direction are formed. Therefore, the noise reduction effect per unit length of the compressor discharge-side piping portion is enhanced, and a high noise reduction effect can be obtained with a simple structure.

(4) In some embodiments, in the noise reduction structure described in (2) above, the plane including the straight line parallel to the tube axis line of the compressor discharge-side piping section and the axis of rotation of the impeller of the compressor is a plane S, And n1 is the number of partition plates positioned on the rotational axis side with respect to the plane S among the number N of the plurality of partition plates, When the number of the partitioning plate portions is n2, the partitioning portion is configured to satisfy n1 < n2.

The flow velocity of the air flowing from the portion of the compressor discharge pipe close to the compressor outlet pipe and the compressor outlet pipe is set such that the flow velocity on the outer peripheral side farther from the axis of rotation of the impeller of the compressor with respect to the plane S Is larger than the flow velocity on the inner peripheral side close to the rotation axis. In this regard, according to the noise reduction structure described in (4) above, the number n1 of partition plates positioned on the rotational axis side (inner circumferential side) with respect to the plane S is smaller than the number n1, (N2) of the partition plate portions located on the outer peripheral side (outer peripheral side), the flow path resistance on the inner peripheral side among the flow path resistance caused by the second perforated plate portion formed along the partition plate portion is made smaller than the flow path resistance on the outer peripheral side . Therefore, the flow velocity distribution in the cross-section of the flow passage can be made uniform.

Therefore, according to the noise reduction structure described in (4) above, the increase in energy loss due to the passage resistance caused by the second perforated plate portion can be suppressed by equalizing the flow velocity distribution. Thereby, it is possible to suppress the noise on the discharge side of the compressor while suppressing the increase in energy loss.

(5) In some embodiments, in the noise reduction structure described in (1), the partition portion has a circular sectional shape so as to divide the internal space of the compressor discharge-side piping portion into two flow paths in the radial direction.

According to the noise reduction structure described in (5), the tubular second perforated plate is formed on the inner side and the outer side of the tubular partition portion concentrically with the partition portion. Thereby, the noise reduction effect per unit length of the compressor discharge side piping portion is enhanced, and a high noise reducing effect can be obtained with a simple structure.

(6) In some embodiments, in the noise reduction structure according to any one of (1) to (5), the compressor discharge pipe section includes the compressor outlet pipe.

According to the noise reduction structure described in (6), by forming the first perforated plate portion and the second perforated plate portion in the compressor outlet pipe, which is a part of the supercharger, regardless of the structure of the pipe connecting the compressor outlet pipe and the air cooler, Noise can be reduced.

(7) In some embodiments, the noise reduction structure according to any one of the above-mentioned (1) to (6) is characterized in that the noise reduction structure includes: And a third porous plate portion having a through hole.

According to the noise reduction structure described in (7), by forming the third perforated plate portion along the inner wall of the fuel chamber of the supercharger, the noise of the supercharger can be reduced irrespective of the structure of the pipe connecting the compressor and the air cooler.

(8) A supercharging apparatus according to at least one embodiment of the present invention comprises a supercharger and the noise reduction structure according to any one of (1) to (7).

According to the supercharger described in (8), since the noise reduction structure according to any one of (1) to (7) is provided, noise on the air discharge side of the compressor can be effectively reduced.

According to at least one embodiment of the present invention, there is provided a noise reduction structure capable of effectively reducing noise on the air discharge side of a compressor in a supercharger, and a supercharger having the same.

1 is a block diagram showing a schematic configuration of an internal combustion engine system 100 according to an embodiment.
2 is a view showing the configuration of the compressor discharge-side pipe 9 (the compressor 8 is viewed from the axial direction).
3 is a schematic cross-sectional view of a noise abatement structure 20 (20A) according to one embodiment.
4 is a schematic cross-sectional view of a noise abatement structure 20 (20B) according to one embodiment.
5 is a schematic cross-sectional view of a noise abatement structure 20 (20C) according to one embodiment.
6 is a schematic cross-sectional view of a noise abatement structure 20 (20D) according to one embodiment.
7 is a schematic cross-sectional view of the noise reduction structure related to the comparative form.
Fig. 8 is a schematic view showing the configuration of the first perforated plate portion 24 and the second perforated plate portion 28. Fig.
9 is a schematic cross-sectional view of the compressor 8 in the turbocharger 4 according to one embodiment, showing a noise reduction structure 20 (20E) according to an embodiment.

Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements and the like of the constituent parts described in the embodiments or shown in the drawings are not intended to limit the scope of the present invention and are merely illustrative examples.

For example, expressions representing relative or absolute arrangements such as "in any direction," "along any direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" Not only the arrangement but also a state in which a tolerance or an angle or a distance with which the same function is obtained is relatively displaced is shown.

For example, expressions indicating that objects such as " same ", " equivalent ", and " homogeneous " are equivalent represent not only strictly equivalent states but also tolerances or differences in degree It is assumed that the state is also indicated.

For example, the expression indicating a shape such as a square shape or a cylinder shape not only shows a shape such as a square shape or a cylindrical shape in a geometrically strict sense, but also includes a concave portion and a chamfer portion in a range in which the same effect can be obtained And the like.

On the other hand, the expression "equipped", "tilted", "equipped", "comprising", or "having" is not an exclusive expression except for the presence of other elements.

1 is a block diagram showing a schematic configuration of an internal combustion engine system 100 according to an embodiment.

1, the internal combustion engine system 100 includes an internal combustion engine 2 (for example, a marine diesel engine), a supercharger 4, and an air cooler 6.

In the illustrated embodiment, the supercharger 4 is an exhaust turbine supercharger (turbo charger). The supercharger 4 drives the turbine 10 coaxially connected to the compressor 8 by using the exhaust gas of the internal combustion engine 2 to compress the air supplied to the internal combustion engine 2 by the compressor 8 . The air compressed by the compressor 8 passes through the compressor discharge side pipe 9 and is led to the air cooler 6. After the air is cooled by the air cooler 6 to increase the air density, .

Fig. 2 is a view showing the configuration of the compressor discharge-side pipe 9 (the compressor 8 is viewed from the axial direction).

2, the compressor discharge-side piping 9 is connected to the compressor outlet 8 on the downstream side of the tongue portion 13 (the connection position of the swirling start of the power supply 12 and the swirl end) of the power supply 12 of the compressor 8, A pipe 14 connecting the compressor outlet pipe 14 and the air cooler 6, and a pipe 15 connecting the compressor outlet pipe 14 and the air cooler 6. The piping 15 includes an expansion joint 16 connected to the downstream end 14a of the compressor outlet pipe 14 and a downstream end 16a of the expansion joint 16 and the air cooler 6, (18) connecting the inlet (6a) of the tube (6).

1 and 2, the internal combustion engine system 100 is provided with a noise reduction structure 20 for reducing noise on the air discharge side of the compressor 8 in the turbocharger 4. The noise reduction structure 20 constitutes the supercharging device 5 together with the supercharger 4. [

Here, the noise reduction structures 20 (20A to 20D) related to some embodiments will be described with reference to Figs. 3 to 6. Fig.

FIG. 3 is a schematic cross-sectional view of a noise abatement structure 20 (20A) according to one embodiment. 4 is a schematic cross-sectional view of a noise abatement structure 20 (20B) according to one embodiment. 5 is a schematic cross-sectional view of a noise abatement structure 20 (20C) according to an embodiment. 6 is a schematic cross-sectional view of a noise reduction structure 20 (20D) according to one embodiment.

3 to 6, the noise reducing structure 20 (20A to 20D) is constituted by a compressor discharge side pipe portion 22 which is at least a portion of the compressor discharge side pipe 9, A first porous plate portion 24, a partition portion 26, and a second porous plate portion 28. [ The compressor discharge-side piping section 22 is a part of the compressor discharge-side piping 9 that includes the first perforated plate section 24, the partitioning section 26, the second perforated plate section 28, As shown in FIG.

The first perforated plate portion 24 is formed along the inner peripheral surface 30 in the circumferential direction of the compressor discharge side piping portion 22 so as to form the air layer 32 between the inner peripheral surface 30 of the compressor discharge side piping portion 22 and the inner peripheral surface 30 of the compressor discharge side piping portion 22. [ And has a plurality of through holes (34). The partition portion 26 divides the internal space 36 of the compressor discharge side piping portion 22 in the radial direction or the circumferential direction of the compressor discharge side piping portion 22, 38). The second perforated plate portion 28 is formed in each of the plurality of flow paths 38 and extends along the partition portion 26 so as to form an air layer 40 between the partition wall portion 26 and the second perforated plate portion 28, And has a hole 42.

According to this configuration, since the first porous plate portion 24, the air layer 32, and the second porous plate portion 28 and the air layer 40 function as acoustic filters, Noise can be reduced.

As compared with the case where only the first perforated plate portion 24 is formed in the compressor discharge side piping portion 22 as shown in Fig. 7, in the noise attenuating structure 20 shown in Figs. 3 to 6, 26 and the second porous plate portion 28 are formed, the installation area of the porous plate portion can be increased. Therefore, the noise reduction effect per unit length of the compressor discharge-side piping section 22 can be enhanced.

8, the hole diameter d, the aperture ratio?, And the hole diameter? Of the through-hole 34 and the through-hole 42 are set so as to correspond to the first and second perforated plate portions 24 and 28, When the thickness L of the air layer 32 and the air layer 40 is set corresponding to the resonance frequency according to the rotation period of the impeller 11 of the compressor 8 (see FIG. 9), the impeller 11 of the compressor 8 ) Can be effectively reduced.

3 to 5, the partitioning portion 26 has a diameter (diameter) such that the internal space 36 of the compressor discharge-side piping portion 22 is divided into a plurality of flow paths 38 in the circumferential direction, And a plurality of partition plates (44) extending in the direction of the partition plate (44). The first perforated plate portion 24 and the second perforated plate portion 28 are formed in each of the plurality of flow paths 38. The second porous plate portion 28 extends in the radial direction along both surfaces of each partition plate portion 44 and the outer edge 29 of the second porous plate portion 28 in the radial direction extends in the first direction And is connected to the perforated plate section 24.

According to this structure, the noise reduction structure 20 can be easily manufactured. For example, the partitioning portion 26 is inserted into the compressor discharge-side piping portion 22 from the one end side of the compressor discharge-side piping portion 22, and the outer end 45 in the radial direction of the partitioning plate portion 44, It is possible to easily fix the partition portion 26 to the compressor discharge side piping portion 22 by joining the partition wall portion 22 to the inner peripheral surface 30 of the compressor discharge side piping portion 22 by welding or the like. Further, since the compressor discharge-side piping section 22 is supported from the inside by the plurality of partition plates 44 extending in the radial direction, the high rigidity can be realized.

3, the partitioning portion 26 has a cross-sectional shape (cross-sectional shape) such that the internal space 36 of the compressor discharge-side piping portion 22 is divided into four flow paths 38 in the peripheral direction, Respectively. In the illustrated embodiment, the second perforated plate portion 28 is extended along both surfaces of the four partition plate portions 44, so that a total of eight second perforated plate portions 28 are formed. Thereby, the noise reduction effect per unit length of the compressor discharge-side piping section 22 is improved, and a high noise reduction effect can be obtained with a simple structure.

In some embodiments, as shown in Figs. 2, 4 and 5, the tube axis center line L1 of the compressor discharge-side piping section 22 and the rotational axis of the impeller 11 (see Fig. 9) The plane including the straight line L3 parallel to the line L2 is set as the plane S and the number of the partition plates 44 arranged on the side of the rotation axis L2 with respect to the plane S If the number of the partitioning plate portions 44 (44a) is n1 and the number of partitioning plate portions 44 (44b) located on the opposite side of the rotation axis L2 with respect to the plane S is n2, the partitioning portion 26 is n1 ≪ n2. In the embodiment shown in Fig. 4, N = 3, n1 = 1 and n2 = 2 are satisfied. In the form shown in Fig. 5, N = 3, n1 = 1, n2 = 0 The number of plates 44 is not counted in either n1 or n2).

The flow velocity of the air flowing in the portion of the compressor discharge pipe 9 close to the compressor outlet pipe 14 and the compressor outlet pipe 14 is determined by the rotational axis of the impeller 11 of the compressor 8 L2 is larger than the flow rate on the inner peripheral side closer to the rotation axis L2 with respect to the plane S than the flow rate on the outer peripheral side. 4 and 5, the number n1 of partition plates 44 (44a) positioned on the side of the axis of rotation L2 (inner circumferential side) with respect to the plane S is smaller than the number n (N2) of the partitioning plate portions 44 (44b) located on the opposite side (outer peripheral side) to the axis of rotation L2 of the second perforated plate portion 28 formed along the partitioning plate portion 44, The flow path resistance on the inner circumferential side can be made smaller than the flow path resistance on the outer circumferential side. Therefore, the flow velocity distribution in the cross-section of the flow passage can be made uniform.

4 and 5, the increase in the energy loss due to the passage resistance caused by the second perforated plate portion 28 can be suppressed by equalizing the flow velocity distribution. Thereby, it is possible to suppress the noise on the discharge side of the compressor (8) while suppressing an increase in energy loss.

6, the partitioning portion 26 has a circular sectional shape so as to divide the internal space 36 of the compressor discharge-side piping portion 22 into two flow paths 38 in the radial direction . That is, in the embodiment shown in Fig. 6, the double tube is constituted by the compressor discharge side piping section 22 and the partitioning section 26. A tubular second porous plate portion 28 (28a) is formed concentrically with the partitioning portion 26 on the inner side of the tubular partitioning portion 26. An annular partitioning portion 26 is formed on the outer side of the tubular partitioning portion 26, And the second perforated plate portion 28 (28b) is formed concentrically with the partition portion 26. Thereby, the noise reduction effect per unit length of the compressor discharge-side piping section 22 is enhanced, and a high noise reduction effect can be obtained with a simple structure.

The above noise reduction structures 20 (20A to 20D) may be applied to either the compressor outlet pipe 14, the expansion joint 16, or the pipe 18 having a different diameter. That is, the compressor discharge-side piping section 22 includes at least one of the compressor outlet pipe 14, the expansion joint 16, and the pipe 18 having a different diameter. If the noise reduction structure 20 (20A to 20D) is applied to the compressor outlet pipe 14 (if the compressor discharge pipe section 22 includes the compressor outlet pipe 14), the compressor 8 and the air cooler It is preferable that the noise of the turbocharger 4 can be reduced regardless of the configuration of the pipe 15 connecting the intake pipe 6 to the engine. When the noise reduction structure 20 (20B or 20C) is applied to the compressor outlet pipe 14 (if the compressor discharge pipe portion 22 shown in FIG. 4 or 5 includes the compressor outlet pipe 14) It is possible to equalize the flow velocity distribution in the flow passage cross section of the compressor outlet pipe 14 as described above, so that the noise on the discharge side of the compressor 8 can be reduced and the increase in energy loss can be suppressed.

9 is a schematic cross-sectional view of the compressor 8 in the turbocharger 4 according to one embodiment, showing a noise reduction structure 20 (20E) according to an embodiment.

In one embodiment, as shown in Fig. 9, the noise reduction structure 20 (20E) includes a third perforated plate portion 52. [ 9, the third perforated plate portion 52 extends along the inner wall 46 so as to form an air layer 48 between itself and the inner wall 46 of the fruit chamber 12, (50). In the exemplary embodiment shown, the third perforated plate portion 52 extends along the inner wall 46 over more than half of the fruit chamber 12.

Also in this configuration, since the third porous plate portion 52 and the air layer 48 function as an acoustic filter, noise on the discharge side of the compressor 8 can be reduced. In addition, the noise of the turbocharger 4 can be reduced irrespective of the configuration of the pipe 15 connecting the compressor 8 and the air cooler 6.

The present invention is not limited to the above-described embodiment, but includes a form in which the above-described embodiment is modified, and a form in which these forms are appropriately combined.

For example, any one of the noise reduction structures 20 (20A to 20D) shown in Figs. 3 to 6 and the noise reduction structure 20 (20E) shown in Fig. 9 may be used in combination It is also possible. That is, the supercharger 5 described above can be configured so that only one of the noise reduction structures 20 (20A to 20D) shown in Figs. 3 to 6 and the noise reduction structure 20 (20E) shown in Fig. 9 Or both of them may be provided.

Further, only one of the noise reduction structures 20 (20A to 20D) may be applied to the compressor discharge side pipe 9, or two or more of them may be applied. For example, the noise reduction structure 20 (20A) shown in FIG. 3 may be applied to the compressor outlet pipe 14, the noise reduction structure 20 (20D) may be applied to at least a part of the pipe 15, A combination may be applied.

Although the exhaust turbo supercharger (turbocharger) is exemplified in the above-described embodiment, the structure of the turbocharger is not limited to this. The power drawn from the output shaft of the internal combustion engine through a belt or the like, or the power of the electric motor, It may be a mechanical supercharger (supercharger) that drives.

2: Internal combustion engine
4: supercharger
5: Supercharger
6: Air cooler
6a: entrance
8: Compressor
9: Compressor discharge side piping
10: Turbine
11: Impeller
12: fruits
13: Tongue
14: compressor outlet pipe
14a: downstream stage
15: Piping
16: Expansion joint
16a: downstream stage
18: Tubes with different diameters
20 (20A, 20B, 20C, 20D): Noise reduction structure
22: Compressor discharge side piping part
24: first perforated plate section
26:
28: the second perforated plate section
29: outer edge
30: inner peripheral surface
32: air layer
34: Through hole
36: Interior space
38: Euro
40: air layer
42: Through hole
44 (44a, 44b): A partition plate
45: outer end
46: inner wall
48: air layer
50: Through hole
52: Third multi-
100: Internal combustion engine system
L1: tube center line
L2: rotation axis line
L3: Straight line
N, n1, n2: number
S: plane

Claims (8)

A noise reduction structure for reducing noise on the air discharge side of a compressor in a supercharger,
A compressor discharge piping portion that is a piping of at least a portion of a compressor discharge piping comprising a compressor outlet pipe on the downstream side of the tongue portion of the compressor and a pipe connecting the compressor outlet pipe and the air cooler,
A first porous plate portion extending along the inner peripheral surface in the circumferential direction of the compressor discharge-side piping portion so as to form an air layer between the inner peripheral surface of the compressor discharge-side piping portion and the plurality of through-
A partitioning portion for partitioning the internal space of the compressor discharge-side piping portion in the radial direction or the circumferential direction of the compressor discharge-side piping portion to form a plurality of flow paths in the compressor discharge-side piping portion;
And a second porous plate portion formed on each of the plurality of flow paths and extending along the partitioning portion so as to form an air layer between the partitioning portion and the plurality of through holes. The method according to claim 1,
Wherein the partition portion includes a plurality of partition plates extending in the radial direction so as to partition the internal space of the compressor discharge side piping portion into the plurality of flow paths in the circumferential direction. 3. The method of claim 2,
Wherein the partition portion has a cross-sectional shape such that the internal space of the compressor discharge-side piping portion is divided into four flow paths in the circumferential direction. 3. The method of claim 2,
A plane including a straight line parallel to a tube axis center line of the compressor discharge side piping section and a rotation axis line of the impeller of the compressor is a plane S,
Wherein the number of the partitioning plate portions positioned on the rotational axis side with respect to the plane S is n1 and the number of the partitioning plate portions located on the side opposite to the rotational axis with respect to the plane S among the number N of the plurality of partitioning plate portions is N1, Is n2,
Wherein the partitioning portion is configured to satisfy n1 < n2. The method according to claim 1,
Wherein the partition portion has a circular sectional shape so as to divide the internal space of the compressor discharge side piping portion into two flow paths in the radial direction. The method according to claim 1,
Wherein the compressor discharge pipe portion includes the compressor outlet pipe. The method according to claim 1,
And a third perforated plate portion extending along the inner wall so as to form an air layer between the inner wall and the inner wall of the fruit chamber and having a plurality of through holes. A supercharger comprising the supercharger and the noise reduction structure according to any one of claims 1 to 7.

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